From 1c4110bd10e8ba8adfba69c15de91365965582d9 Mon Sep 17 00:00:00 2001
From: Nathan Scott <nathans@sgi.com>
Date: Thu, 18 May 2006 15:52:48 +0000
Subject: [PATCH] Provide a mechanism for batch writeout of buffer cache nodes.
 Merge of master-melb:xfs-cmds:25968a by kenmcd.

---
 include/cache.h |  3 +++
 libxfs/cache.c  | 24 +++++++++++++++++++++---
 libxfs/rdwr.c   |  2 ++
 3 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/include/cache.h b/include/cache.h
index 85dce63a6..3cccbd831 100644
--- a/include/cache.h
+++ b/include/cache.h
@@ -33,12 +33,14 @@ typedef struct cache_node * (*cache_node_alloc_t)(void);
 typedef void (*cache_node_relse_t)(struct cache_node *);
 typedef unsigned int (*cache_node_hash_t)(cache_key_t, unsigned int);
 typedef int (*cache_node_compare_t)(struct cache_node *, cache_key_t);
+typedef unsigned int (*cache_bulk_relse_t)(struct cache *, struct list_head *);
 
 struct cache_operations {
 	cache_node_hash_t	hash;
 	cache_node_alloc_t	alloc;
 	cache_node_relse_t	relse;
 	cache_node_compare_t	compare;
+	cache_bulk_relse_t	bulkrelse;	/* optional */
 };
 
 struct cache {
@@ -49,6 +51,7 @@ struct cache {
 	cache_node_alloc_t	alloc;		/* allocation function */
 	cache_node_relse_t	relse;		/* memory free function */
 	cache_node_compare_t	compare;	/* comparison routine */
+	cache_bulk_relse_t	bulkrelse;	/* bulk release routine */
 	unsigned int		c_hashsize;	/* hash bucket count */
 	struct cache_hash	*c_hash;	/* hash table buckets */
 };
diff --git a/libxfs/cache.c b/libxfs/cache.c
index 93bb0e644..587ab1a71 100644
--- a/libxfs/cache.c
+++ b/libxfs/cache.c
@@ -28,6 +28,8 @@
 
 #define CACHE_DEBUG 1
 
+static unsigned int cache_generic_bulkrelse(struct cache *, struct list_head *);
+
 struct cache *
 cache_init(
 	unsigned int		hashsize,
@@ -52,6 +54,8 @@ cache_init(
 	cache->alloc = cache_operations->alloc;
 	cache->relse = cache_operations->relse;
 	cache->compare = cache_operations->compare;
+	cache->bulkrelse = cache_operations->bulkrelse ?
+		cache_operations->bulkrelse : cache_generic_bulkrelse;
 	pthread_mutex_init(&cache->c_mutex, NULL);
 
 	for (i = 0; i < hashsize; i++) {
@@ -170,7 +174,6 @@ cache_shake_hash(
 	struct list_head *	n;
 	struct cache_node *	node;
 	unsigned int		inuse = 0;
-	unsigned int		count = 0;
 
 	list_head_init(&temp);
 	head = &hash->ch_list;
@@ -186,8 +189,23 @@ cache_shake_hash(
 			break;
 	}
 	pthread_mutex_unlock(&hash->ch_mutex);
-	while (!list_empty(&temp)) {
-		node = (struct cache_node *)temp.next;
+	return cache->bulkrelse(cache, &temp);
+}
+
+/*
+ * Generic implementation of bulk release, which just iterates over
+ * the list calling the single node relse routine for each node.
+ */
+static unsigned int
+cache_generic_bulkrelse(
+	struct cache *		cache,
+	struct list_head *	list)
+{
+	struct cache_node *	node;
+	unsigned int		count = 0;
+
+	while (!list_empty(list)) {
+		node = (struct cache_node *)list->next;
 		pthread_mutex_destroy(&node->cn_mutex);
 		list_del_init(&node->cn_list);
 		cache->relse(node);
diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 501efff1b..0d0f9d83c 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -447,6 +447,7 @@ struct cache_operations libxfs_bcache_operations = {
 	/* .alloc */	libxfs_balloc,
 	/* .relse */	libxfs_brelse,
 	/* .compare */	libxfs_bcompare,
+	/* .bulkrelse */ NULL	/* TODO: lio_listio64 interface? */
 };
 
 
@@ -650,4 +651,5 @@ struct cache_operations libxfs_icache_operations = {
 	/* .alloc */	libxfs_ialloc,
 	/* .relse */	libxfs_irelse,
 	/* .compare */	libxfs_icompare,
+	/* .bulkrelse */ NULL
 };
-- 
2.47.2